. >> reporter: for 75 years, the bay bridge has been the workhorse on san francisco bay, linking oakland and san francisco, and carrying 270,000 cars and trucks a day. on the san francisco side, its towers support suspension cables that keep the bridge up. but this gray, utilitarian structure that partially collapsed in the 1989 earthquake has never captured the world's attention, the way its nearby cousin, the golden gate bridge has. built toward the end of the depression, both were engineering marvels. now, the bay bridge is making its own splash. on a cold rainy night last week it was transformed into a giant work of art. 25,000 tiny white undulating l.e.d. lights, strung from the vertical cables, were turned on in a flashy display of public art that can be seen for miles. for california politicians like lieutenant governor gavin newsom, it was a chance to tout the area's uniqueness. >> here we are in san francisco- - a wacky and wonderful place and a city that is probably best described as 49 square miles surrounded by reality. a city of dreamers of doers of entrepreneurs and innovat